We use standard Docker images, published on Docker Hub,
and the related Dockerfile (the description file which describes the docker image / environment,
and which is directly used to build the image) can be found on GitHub.

Every build runs in a new VM (which is destroyed right after the build),
not just in a new container! This allows us to grant you full control over Docker
and the whole environment.

When your build starts on the Docker based Stack we volume mount the /var/run/docker.sock socket
into your container (similar to calling docker run -v /var/run/docker.sock:/var/run/docker.sock ...;
you can find a description about this access granting method at:
https://jpetazzo.github.io/2015/09/03/do-not-use-docker-in-docker-for-ci/).
Note: The docker binary have to be installed inside the base Docker image
(we install Docker in every one of our Docker images so that you don't have to do anything if you use our image,
or you base your own image on our Docker images),
because docker started to migrate from a single-binary solution to dynamically loaded components,
and simply sharing the docker binary is not sufficient anymore.

This means that you have access to docker in your container, and can use other tools which use docker,
like docker-compose.
You can, for example, configure and run tests and other automations on website projects using docker-compose.

You can call docker info, docker build, docker run, docker login, docker push,
etc. exactly how you would on your own machine.

Important Note if you want to run docker in your build, and share volumes: because of how docker handles volume sharing,
only those volumes can be shared which are shared with the base docker container (the one your build is running in).
Everything under /bitrise can be mounted as a volume, but no other path is guaranteed to work with --volume mapping.

Practically this means that if you use the standard paths and you use relative paths to mount volumes it'll work as expected,
as the default source code directory is located inside /bitrise (by default it's /bitrise/src in our Docker images).
What won't work is if you change the source code directory to be located outside of /bitrise,
or you want to mount a folder with an absolute path outside of /bitrise.